The invention deals with a process for the laying of high pressure fluid pipelines, particularly gas pipelines, inside already existing old fluid pipelines.
High pressure fluid pipelines in the form of gas pipelines are running throughout the country and are linked at many points in the manner of a grid. Some of the gas pipelines feature different nominal pressure stages between sub-mains or connecting points thus calling for pressure reduction or compressor stages between the various pipelines of different nominal pressure stages. This obviously renders these installations more expensive and, further-more, the throughput is restricted by the pipeline section of the lowest nominal pressure. The conversion of pipelines of different nominal pressure stages to a standardised higher nominal pressure stage is relatively expensive because the pipeline sections of an excessively low nominal pressure stage have to be completely laid anew.
The so called woven fabric hose relining process is used for the restructuring of gas pipe-lines, for example as known from DE-A-44 03 370. For this purpose, a woven fabric hosexe2x80x94a so called inlinerxe2x80x94with resin impregnated inner coating is turned inside out and inserted into the gas pipeline to be restructured, in such a manner that the resin impregnated coating is now on the outside. With the aid of the application of pressure, the resin impregnated outer coat adheres to the inside of the old fluid pipeline. Gas pipelines of a given nominal pressure stage are thus restructured, in such a manner that the restructured gas pipeline is once again of the identical or lower nominal pressure stage.
A woven fabric hose relining process is also known from U.S. Pat. No. 5,205,886, by which an inliner is inserted into an existing pipeline. The inliner consists of several coats of a tension and tear proof outer coating made of woven fabric. All coatings of the inliner are elastic and expandable, in such a manner that the inserted inliner can be expanded with the aid of a fluid and brought into close contact with the inner wall of the pipeline. The pressure stability is thus chiefly a function of the old fluid pipeline.
The object of the present invention consists of a process for the laying of high pressure fluid pipelines, which is simpler and cheaper.
This problem is solved by laying of high pressure fluid pipelines of a given nominal pressure stage inside an already existing old fluid pipeline of an old nominal pressure stage by inserting a woven fabric hose of the given nominal pressure stage into the old fluid pipeline, characterized in that the given nominal pressure stage of the woven fabric hose is higher than the old nominal pressure stage of the old fluid pipeline.
The core of the invention consists of the fact that known processes for the restructuring of pipelines with the aid of woven fabric hose relining can also be used in order to raise the nominal pressure stage of still sound high pressure fluid pipelines. It is thus possible to obtain high pressure fluid pipelines of higher nominal pressure stages, without having to excavate the old fluid pipeline.
According to a preferred embodiment, the inserted woven fabric hose is coated, whereby the type of coating is chosen as a function of the pressures of the gases and fluids conveyed through the high pressure fluid pipeline. According to a further embodiment of the invention, the woven fabric hose of the given nominal pressure stage is inserted into a number of interconnected old fluid pipelines of different nominal pressure stages, whereby the given nominal pressure stage of the woven fabric hose is higher than at least one of the different old nominal pressure stages of the old fluid pipeline.
According to a further preferred embodiment of the invention, the outer diameter of the inserted woven fabric hose approximately equals the inner diameter of the old fluid pipeline, in such a manner that no volume is wasted. An important feature is the fact that the outer fluid pipeline does not have to absorb the new nominal pressure, in other words does not have to assume a supporting function. The new higher nominal pressure is fully guaranteed by the stability of the woven fabric. All high strength materials and, particularly, aramid fibers such as those sold under the trademark KEVLAR(copyright), are suitable materials for the woven fabric hose.
In accordance with a further preferred embodiment, the woven fabric hose is inserted into the old fluid pipeline according to the woven fabric hose relining process. It is thus possible to make use of the devices and processes known from the woven fabric relining process when laying high pressure fluid pipelines in accordance with the present invention. invention.
According to an embodiment of the invention, the coating of the fabric hose consists of plastic. Whether or not the coating is plastic, the fabric hose may be coated on the inside and/or outside.
Further details, features and advantages presented by the invention are shown by the description below of a preferred embodiment of the invention, with the aid of the drawings.